Frayed Soooo.... Why did my string loop wear and break?

[ItzaKen]

I tested the nocks for whatever, with a teased, cotton swab; nothing.
I cleaned the wax and crud out of the nocks and retested; nothing.

I'm twisting up another string and will round off everything with a little sandpaper.  I won't have results for a couple of weeks of drawing the bow, but will get back and post results.

Here's the suggestion/recommendation a bowmaker sent me:
"I would just use some 320 grit sandpaper and make sure nothing is sharp in the grooves. I wouldn't worry about finish unless you think you sanded into the wood substantially. Our finish is an epoxy finish similar to Thunderbird. Small defects just use a drop of super glue to seal."

[ItzaKen]

Question:  Has anyone served the 2-3" that will become the loops, before continuing the making of the Flemish loops??

[Roy from Pa]

Never have for a Flemish string but that is how endless loop strings are made.

[Kirkll]

This may sound silly…. But have you checked how the limbs are tracking through the draw cycle?  Just hook the grip on a door knob on an open door and draw the bow and watch what the limbs are doing as you bring it to full draw. Then switch and hook the string on the door knob and watch the back of the limb.

Sometimes a limb will develop a slight twist that you can’t see until you watch the limbs as you draw the bow. That would definitely put more pressure on one side of the string loop.

I would also recommend going to a D97 fast flight string with padded loops.

Kirk

[ItzaKen]

Interesting idea, Kirk.  I can't imagine how/why a lam bow would do that and would be happy to hear how and what any remedy might be!

Yes, I AM ordering some D97.

[Kirkll]

Brother.... You would be amazed at what some of these bullet proof glass bows can do under the right conditions. Just having a string sitting off center in the string grooves and leaving it in direct sun light  for a couple hours can develop a slight limb twist. Heaven forbid you leave a bow strung up in a pick up cab in sunny weather. I've seen them come apart doing that...

With flemish twist strings, sometimes just flipping the loop 180 degrees can make the difference on a slightly twisted limb making it worse, or straightening it back out. This isn't a reflection on the string maker at all, it's just the nature of the beast using a flemish loop.

I think the first time i realized this was while i was building a light weight set of recurve limbs that i had too much forward taper in the core. These limbs would go sideways on you if you breathed on them wrong. Seriously sensitive to perfect string alignment. I finally got it tracking straight and setting in the string grooves nicely. So I finish sanded the limbs and strung it back up only to  find i still had a slight limb twist. That's when i tried flipping the loop 180 degrees.... BINGO!  I was back on track.

For you guys out there that have a slight tracking issues on recurve limbs,or a wee bit of limb twist at brace,  i'd strongly recommend trying flipping the loops 180 before trying to straighten a limb. 

Another thing that can foul up your tracking and cause limb twist is having your loop too tight on that bottom limb, and not checking it closely after you string it for laying dead center. This can even cause problems for bows with excellent stability qualities too.   I always order large loops both ends on my flemish twist strings so they self center easily and rarely bind up in the string notches.  .02 cents worth... 

 Kirk

[ItzaKen]

WOW!!  So much, I did not know!!!  Thank you.

What do you mean by "too tight" on the bottom nock?  I try to make my loops small, so they don't fall off, when the bow's unstrung....

[CoilSpring]

"I make my loops small".....
Like several mentioned, a sharp (or less rounded) edge across the groove path, along which the string loop follows, is very common.  But, also, a smaller string loop, naturally, lays the string more acutely around any sharp edge.  A more acute string angle (due to the smaller diameter loop) over any edge increases force between the edge and string.  Greater force over a smaller area (edge) = increased pressure.  Increased pressure cuts strings.  A larger loop would decrease pressure, due to its obtuse angle, but the real problem is usually a sharp edge perpendicular to the string, how/where yours is cut. 

I like smaller loops, too, but without a sharp edge, small loops are not a problem.  Scissors cut strings really well, when that string is bent around its two edges.

[ItzaKen]

Very interesting explanation!  I'm in the middle of twisting up a string, right now and just finished the bottom loop.  I'll slip this over my limb tip and play with it to see what you're talking about.  I have yet to sand/round the nock edges.

Thanks!!

[V I Archer]

I have a PSE Heritage longbow that does that to strings. I build a flemish twist and then wrap the loops with dacron. Kind of winds up looking like an endless loops string. They last forever this way, just one extra step and a bit more weight, but I killed a few critters with that bow just the same.

[ItzaKen]

I kinda thought this and it's good to see you verify!!
Thanks!

[SlowBowKing]

Had a very similar experience last week!

I think mine was a sharp edge on the notch. I told my buddy about it, and he said “that’s what you get for stringing your bow every time you shoot!”

 And I was just getting ready to set up a new string and have this older one for my backup… 

[ItzaKen]

OUCH!!  That looks scary!

[Kirkll]

WOW!!  So much, I did not know!!!  Thank you.

What do you mean by "too tight" on the bottom nock?  I try to make my loops small, so they don't fall off, when the bow's unstrung....

That may be causing your wear issue right there using the small loops, but the shape may be an issue too. I've got a 3 part series video on tip overlays and shaping them correctly. In this clip it explains why you need a perfect tear drop shape to keep the string loop from moving while drawing the bow. A larger loop is very desirable for this reason.  I know it makes stringing the bow a bit more challenging with larger loops. But its well worth the effort not having the string bind up in the tip notches and string wear too....    check this out.   Kirk

[ItzaKen]

Thank you!... Will watch right now.  :=)

[4 point]

Are you loops a little to big and rubbing where the string nocks are cut around the belly side of the bow? Definitely a sharp spot somewhere.